slope line coloring not working?

[11elevenths]

I can get altitude to color the line properly but not slope unless I try to enter values manually and it's still not what I want.  I tested other tracks and it works on them.  How do I get the line to be colored with red as uphill and blue as downhill with darker shades as higher slope angle???  Used to work fine?  See attached gpx.

[winice]

I tried to set color based on slope. But then I set manual and enter range -5 to 10. Now I can see some easy sections and some difficult sections.

[Menion]

Hello guys,
there seems to be quite a big jumps in the point altitude, so you probably see a coloring, but only on a few points.
If you use the method in the track menu "Update elevation", the app computes elevation from offline files and the result will be most probably a lot better!
Or use the method suggested by @winice that should solve this issue as well!

[11elevenths]

Both methods worked!  Thank you both